Techniques for crosslinking resins with active energy rays such as UV (ultraviolet rays) or EB (electron beam) are widely known. Situations in which such techniques are utilized instead of conventional curing reactions triggered by heat have been increasing.
Active energy ray-curing techniques have improved productivity when compared to thermosetting techniques, due to requirement of less solvent, less energy, and less space in the curing process as well as an ability to complete the reaction in a short time in general. In addition, since light can be irradiated uniformly on a substrate having a complex shape, an active energy ray-curing technique has the benefit that it is easy to achieve higher functionality. These techniques are thus used in applications such as inks, paints, adhesives, sealing materials, electrical and electronic precision components, molded articles and the like.
Some of the major characteristics required for resins in the above-described fields include durability, heat resistance, weatherability, water resistance, permeability of moisture and gas, and the like. An example of a resin which has a combination of such characteristics is a polyisobutylene polymer.
The (meth)acryloyl-terminated polyisobutylene described in Patent Literature 1 is known as a resin having a photocrosslinkable group on a polyisobutylene end. In the technique disclosed in Patent Literature 1, the synthesis pathway of the (meth)acryloyl-terminated polyisobutylene is an extremely long linear synthesis method, and the chlorine atoms that inherently remain in the obtained resin may be undesirable depending on the application.
Patent Literature 2 discloses a technique relating to a (meth)acryloyl-terminated polyisobutylene polymer that essentially does not contain halogen atoms. However, the disclosed synthesis method is complex, and the silane compound and platinum catalyst required for synthesis are very expensive. Therefore, there were large economic limitations to industrial production. Further, this method requires an irradiation of light in an amount of as large as 2,000 J to cure the obtained curable composition. Accordingly, there is a need for a polymer that can be synthesized more simply and that can be cured by an irradiation of a small amount of light.
Patent Literature 3 discloses a technique that functionalizes a polyisobutylene terminal with a phenoxy derivative. However, there are no specific examples showing the presence of the polymer with unhydrolyzed terminals under a condition wherein a compound having a phenoxy group and a (meth)acryloyl ester group is used as an end cap agent and a Lewis acid coexists during a reaction and a post-treatment. Moreover, it is unclear whether the obtained polymer is actually cured with active energy rays, and further, the activity of this polymer is also unclear.
Patent Literature 4 discloses a technique that introduces an alkenyl group onto an isobutylene polymer end by a Friedel-Crafts reaction. Patent Literature 4 only describes that this alkenyl-terminated polyisobutylene polymer can be cured by forming a bond by a hydrosilylation reaction with a hydrosilane compound in the presence of a platinum catalyst.